International Rectifier IRAUDAMP10 Reference Manual

IRAUDAMP10

300W x 2 Channel Class D Audio Power Amplifier

Using the IRS2052M and IRF6775

By

Jun Honda, Yasushi Nishimura and Liwei Zheng

International Rectifier suggests the following guidelines for safe operation and handling of
IRAUDAMP10 Demo board;

 Always wear safety glasses whenever operating Demo Board
 Avoid personal contact with exposed metal surfaces when operating Demo Board
 Turn off Demo Board when placing or removing measurement probes

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CAUTION:

IRAUDAMP10 REV 1.1

TABLE OF CONTENTS PAGE

INTRODUCTION ............................................................................................................................................... 3

SPECIFICATIONS ............................................................................................................................................ 3

CONNECTION SETUP ..................................................................................................................................... 5

CONNECTOR DESCRIPTION ......................................................................................................................... 5

TEST PROCEDURES ....................................................................................................................................... 6

PERFORMANCE AND TEST GRAPHS .......................................................................................................... 7

SOFT CLIPPING ............................................................................................................................................. 10

EFFICIENCY ................................................................................................................................................... 11

THERMAL CONSIDERATIONS ..................................................................................................................... 11

THERMAL INTERFACE MATERIAL’S PRESSURE CONTROL ................................................................................. 12

POWER SUPPLY REJECTION RATIO (PSRR) ............................................................................................ 14

SHORT CIRCUIT PROTECTION RESPONSE .............................................................................................. 15

IRAUDAMP10 OVERVIEW ............................................................................................................................ 16

FUNCTIONAL DESCRIPTIONS ..................................................................................................................... 18

IRS2052M GATE DRIVER IC ......................................................................................................................... 18

SELF-OSCILLATING FREQUENCY .................................................................................................................... 19

ADJUSTMENTS OF SELF-OSCILLATING FREQUENCY ......................................................................................... 19

INTERNAL CLOCK OSCILLATOR ....................................................................................................................... 19

SELECTABLE DEAD-TIME ................................................................................................................................ 20

PROTECTION SYSTEM OVERVIEW ............................................................................................................ 21

CLICK AND POP NOISE REDUCTION ......................................................................................................... 23

BUS PUMPING ............................................................................................................................................... 24

INPUT SIGNAL AND GAIN SETTING ........................................................................................................... 24

GAIN SETTING ............................................................................................................................................... 25

IRAUDAMP10 FABRICATION MATERIALS ................................................................................................. 27

IRAUDAMP10 PCB SPECIFICATIONS ......................................................................................................... 31

REVISION CHANGES DESCRIPTIONS ........................................................................................................ 34

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IRAUDAMP10 REV 1.1

Introduction

The IRAUDAMP10 Demo board is a reference design which uses only one IC (IRS2052M) to derive
appropriate input signals, amplify the audio input, and achieve a two-channel 280 W/ch (4Ω, THD+N=1%)
half-bridge Class D audio power amplifier. The reference design demonstrates how to use the IRS2052M
Class D audio controller and gate driver IC, implement protection circuits, and design an optimum PCB
layout using IRF6775 DirectFET MOSFETs. The reference design contains all the required housekeeping
power supplies for ease of use. The two-channel design is scalable, for power and number of channels.

Applications

 AV receivers
 Home theater systems
 Mini component stereos
 Powered speakers
 Sub-woofers
 Musical Instrument amplifiers
 Automotive after market amplifiers

Features

Output Power: 300W x 2 channels (4Ω, THD+N=1%)

or 370W x 2 channels (4Ω, THD+N=10%)
Residual Noise: 220V, IHF-A weighted, AES-17 filter
Distortion: 0.008% THD+N @ 100W, 4Ω
Efficiency: 90% @ 300W, 4Ω, single-channel driven, Class D stage
Multiple Protection Features: Over-current protection (OCP), high side and low side

Over-voltage protection (OVP),

Under-voltage protection (UVP), high side and low side

Over-temperature protection (OTP)
PWM Modulator: Self-oscillating half-bridge topology with optional clock synchronization

Specifications

General Test Conditions (unless otherwise noted) Notes / Conditions

Supply Voltages ±50V
Load Impedance 4Ω
Self-Oscillating Frequency 500kHz No input signal, Adjustable
Gain Setting 30.8dB 1Vrms input yields rated power

Electrical Data Typical Notes / Conditions

IR Devices Used IRS2052M Audio Controller and Gate-Driver,

IRF6775 DirectFET MOSFETs
Modulator Self-oscillating, second order sigma-delta modulation, analog input
Power Supply Range ± 25V to ±50V Bipolar power supply
Output Power CH1-2: (1% THD+N) 300W 1kHz, ±50V
Output Power CH1-2: (10% THD+N) 370W 1kHz, ±50V

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IRAUDAMP10 REV 1.1



Rated Load Impedance 8-4Ω Resistive load
Standby Supply Current +45/-95mA No input signal
Total Idle Power Consumption 7W No input signal
Channel Efficiency 90% Single-channel driven,

300W, Class D stage

.

Audio Performance Class D

Output

THD+N, 1W
THD+N, 20W
THD+N, 100W
THD+N, 200W

Dynamic Range 100dB

Residual Noise, 22Hz - 20kHzAES17

Damping Factor 51 1kHz, relative to 4Ω load
Channel Separation 74dB

Frequency Response : 20Hz-20kHz

: 20Hz-35kHz

Physical Specifications

Dimensions 3.94”(L) x 2.83”(W) x 0.85”(H)

Weight 0.130kgm

0.015%

0.009%

0.008%

0.015%

220

74dB
70dB
±1dB
±3dB

100 mm (L) x 72 mm (W) x 21.5 mm(H)

Notes / Conditions

1kHz, Single-channel driven

A-weighted, AES-17 filter,
Single-channel operation
Self-oscillating – 500kHz

V

100Hz
1kHz
10kHz

1W, 4Ω - 8Ω Load

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IRAUDAMP10 REV 1.1

Connection Setup

Fig 1 Typical Test Setup

Connector Description

Pin # Pin Name Pin Description

CN1

P1

P2

P3

1 CH1 INPUT Analog input for CH1
2 GND Floating ground of Channel 1 input
3 GND Floating ground of Channel 2 input
4 CH2 INPUT Analog input for CH2
1 -B -50V supply referenced to GND.
2 GND Ground signal from MB.
3 +B +50V supply referenced to GND.
1 CH2 OUTPUT Output of Channel 2
2 GND Floating ground of Channel 2 output
1 GND Floating ground of Channel 1 output
2 CH1 OUTPUT Output of Channel 1

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IRAUDAMP10 REV 1.1

Test Procedures

Test Setup:

1. Connect 4-200 W dummy loads to 2 output connectors (P2 and P3 as shown on Fig 1)
and an Audio Precision analyzer (AP).

2. Connect the Audio Signal Generator to CN1 for CH1~CH2 respectively (AP).

3. Set up the dual power supply with voltages of ±50V; current limit to 5A.

4. TURN OFF the dual power supply before connecting to On of the unit under test (UUT).

5. Connect the dual power supply to P1. as shown on Fig 1

Power up:

6. Turn ON the dual power supply. The ±B supplies must be applied and removed at the
same time.

7. One orange and two blue LED should turn ON immediately and stay ON

8. Quiescent current for the positive supply should be 45mA 10mA at +50V.

9. Quiescent current for the negative supply should be 95mA 10mA at –50V.

Switching Frequency test

10. With an Oscilloscope, monitor the switching waveform at test points VS1~VS2. Adjust
VR1A and VR1B to set the self oscillating frequency to 500 kHz  25 kHz when DUT in
free oscillating mode.

Functionality Audio Tests:

11. Set the signal generator to 1kHz, 20 mV

12. Connect the audio signal generator to CN1(Input of CH1,CH2,CH3)

13. Sweep the audio signal voltage from 15 mV

14. Monitor the output signals at P2/P3 with an oscilloscope. The waveform must be a non
distorted sinusoidal signal.

15. Observe that a 1 V

input generates an output voltage of 34.88 V

RMS

ratio, R4x/(R3x) and R30x/(R31x), determines the voltage gain of IRAUDAMP10.

output.

RMS

RMS

to 1 V

RMS

.

(CH1/CH2). The

RMS

Test Setup using Audio Precision (Ap):

16. Use an unbalanced-floating signal from the generator outputs.

17. Use balanced inputs taken across output terminals, P2 and P3.

18. Connect Ap frame ground to GND at terminal P1.

19. Select the AES-17 filter(pull-down menu) for all the testing except frequency response.

20. Use a signal voltage sweep range from 15 mV

21. Run Ap test programs for all subsequent tests as shown in Fig 2- Fig 7below.

to 1.5 V

RMS

RMS

.

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IRAUDAMP10 REV 1.1

Performance and test graphs

10

5

2

1

0.5

0.2

0.1

%

0.05

0.02

0.01

0.005

0.002

0.001
100m 500200m 500m 1 2 5 10 20 50 100 200

ColorSweep Trace Line Style Thick Data A xis C omm ent

1 1 Blue Solid 2 Anlr.TH D+N Ratio Left CH2
1 3 M agenta Solid 2 Anlr.THD+ N Ratio Left CH1

±B Supply = ±50V, 4 Ω Resistive Load

Fig 2 IRAUDAMP10, THD+N versus Power, Stereo, 4 Ω

W

.

+4

+2

+0

d

-2

B

r

-4

A

-6

-8

-10
20 200k50 100 200 500 1k 2k 5k 10k 20k 50k 100k

Hz

ColorSweep Trace Line Style Thick Data Axis Comment

1 1 Blue Solid 2 Anlr.Level B Left CH2
1 2 Magenta Sol id 2 Anlr. Level A Left CH1

T

±B Supply = ±50V, 4 Ω Resistive Load

Fig 3 IRAUDAMP10, Frequency response

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IRAUDAMP10 REV 1.1

100

10

1

0.1

%

0.01

0.00 1

0.0001
20 20k50 100 200 500 1k 2k 5k 10k

Hz

Col orSweep Trace Line St yle Thick Data Axi s Comment

1 1 Green Solid 2 Anlr.THD+N Ratio Left 10W
2 1 Yell ow Solid 2 Anlr.THD+N Ratio Left 50W
3 1 Red Sol i d 2 A nl r . THD+N Rati o Left 100W

Fig 4 THD+N Ratio vs. Frequency

+0

-10

-20

-30

-40

d

-50

B

-60

V

-70

-80

-90

-100

-110
10 20k20 50 100 200 500 1k 2k 5k 10k

ColorSweep Trace Line Sty le Thick Data Axis Comm ent

1 1 Blue Solid 2 Fft.Ch.1 Ampl Left CH2
1 2 Magenta S olid 2 Fft.Ch.2 Am pl Left CH1

Hz

Fig 5, 1V output Frequency Spectrum

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IRAUDAMP10 REV 1.1

+20

+0

-20

-40

d

-60

B
V

-80

-100

-120

-140

10 20k20 50 100 200 500 1k 2k 5k 10k

Hz

ColorSweep Trace Line Style Thick Data Axis Comment

1 1 Blue S olid 2 Fft.Ch.1 Ampl Left CH2
1 2 Magenta S olid 2 Fft.Ch.2 Ampl Left CH1

No signal, Self Oscillator @ 500kHz

Fig 6, IRAUDAMP10 Noise Floor

.

+0

-10

-20

-30

-40

d
B

r

-50

A

-60

-70

-80

-90

-100
20 20k50 100 200 500 1k 2k 5k 10k

ColorSweep Trace Line Style Thick D ata Axis Comm ent

1 1 Blue Solid 2 Anlr.Ampl Left CH2-CH1
1 2 Magenta Solid 2 Anlr.Ampl Left CH1-CH2

Fig 7, Channel separation vs. frequency

Hz

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.

IRAUDAMP10 REV 1.1

Soft Clipping

IRS2052M has Clipping detection function, it monitors error voltage in COMP pin with a window
comparator and pull an open drain nmos referenced to GND. Threshold to detect is at 10% and
90% of VAA-VSS. Each channel has independent CLIP outputs. Once IRS2052M detects
Clipping, the CLIP pin can generate pulses to trigger soft clipping circuit, which can limit output’s
maximum power as Fig 9(soft clipping circuit is not available on AMP10 reference board).

Soft Clipping

Audio signal INPUT

C0A

10uF,50V

R27A

3.3K

R28A

1K

C15A

10uF, 16V

VSS

R29A

220K

D

S

GND

D3A

1N4148

Q6
MMBFJ112

R7A

470K

G

C6A

1uF,50V

R5A

47K

R6A

47K

C5A

10uF, 50V

R3A 1K

Fig 9 Soft Clipping Circuit

Q5
DTA144EKA

GND

VAA

CLIP Detection

IN-

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IRAUDAMP10 REV 1.1

)

Efficiency

Fig 10 shows efficiency characteristics of the IRAUDAMP10. The high efficiency is achieved by
following major factors:

1) Low conduction loss due to the DirectFETs offering low R

2) Low switching loss due to the DirectFETs offering low input capacitance for fast rise and
fall times

Secure dead-time provided by the IRS2052M, avoiding cross-conduction.

Efficiency (%)

100%

90%

80%

DS(ON)

70%

60%

AMP10 50V 4ohms

50%

40%

30%

Efficiency (%

20%

10%

0%

0 50 100 150 200 250 300 350

Output power (W)

Fig 10, IRAUDAMP10 4 ohms load Stereo, ±B supply = ±50V

Thermal Considerations

With this high efficiency, the IRAUDAMP10 design can handle one-eighth of the continuous rated
power, which is generally considered to be a normal operating condition for safety standards,
without additional heatsinks or forced air-cooling.

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IRAUDAMP10 REV 1.1